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DTC P0638:00 [PCM (SKYACTIV-G 2.0)]

DTC P0638:00

Throttle valve actuator control range/performance problem

DETECTION CONDITION

  • The PCM compares the actual TP with the target TP. If the difference is more than the threshold value, the PCM determines that there is a throttle valve actuator control range/performance problem.

    Diagnostic support note

  • This is a continuous monitor (CCM).

  • The check engine light illuminates if the PCM detects the above malfunction condition during the first drive cycle.

  • FREEZE FRAME DATA/Snapshot data is available.

  • DTC is stored in the PCM memory.

FAIL-SAFE FUNCTION

  • Restricts the upper limit of the engine speed.

  • Stops the drive-by-wire control (throttle valve is open at approx. 8 ° by return spring force).

POSSIBLE CAUSE

  • Throttle body connector or terminals malfunction

  • Short to ground in wiring harness between the following terminals:

    • Throttle body terminal E—PCM terminal 1CG

    • Throttle body terminal F—PCM terminal 1CC

  • PCM connector or terminals malfunction

  • Short to power supply in wiring harness between the following terminals:

    • Throttle body terminal E—PCM terminal 1CG

    • Throttle body terminal F—PCM terminal 1CC

  • Open circuit in wiring harness between the following terminals:

    • Throttle body terminal E—PCM terminal 1CG

    • Throttle body terminal F—PCM terminal 1CC

  • Throttle valve actuator malfunction

  • Throttle valve malfunction

  • PCM malfunction

Diagnostic Procedure

STEP

INSPECTION

ACTION

1

 IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA

Yes

Go to the next step.

No

Go to the troubleshooting procedure for DTC on FREEZE FRAME DATA.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

2

 RECORD VEHICLE STATUS AT TIME OF DTC DETECTION TO UTILIZE WITH REPEATABILITY VERIFICATION

NOTE:

  • Recording can be facilitated using the screen capture function of the PC.

  • Record the FREEZE FRAME DATA/snapshot data on the repair order.

—

Go to the next step.

3

 VERIFY RELATED REPAIR INFORMATION AVAILABILITY

  • Verify related Service Bulletins and/or on-line repair information availability.

  • Is any related repair information available?

Yes

Perform repair or diagnosis according to the available repair information.

  • If the vehicle is not repaired, go to the next step.

No

Go to the next step.

4

 INSPECT THROTTLE BODY CONNECTOR CONDITION

  • Switch the ignition off.

  • Disconnect the throttle body connector.

  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).

  • Is there any malfunction?

Yes

Repair or replace the connector and/or terminals, then go to Step 10.

No

Go to the next step.

5

 INSPECT THROTTLE VALVE ACTUATOR CIRCUIT FOR SHORT TO GROUND

  • Verify that the throttle body connector is disconnected.

  • Inspect for continuity between the following terminals (wiring harness-side) and body ground:

    • Throttle body terminal E

    • Throttle body terminal F

  • Is there continuity?

Yes

Disconnect the PCM connector and inspect the wiring harness for short to ground.

  • If the short to ground circuit could be detected in the wiring harness:

    • Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:

      • Throttle body terminal E—PCM terminal 1CG

      • Throttle body terminal F—PCM terminal 1CC

        If there is a common connector:

      • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.

      • Repair or replace the malfunctioning part.

        If there is no common connector:

      • Repair or replace the wiring harness which has a short to ground.

Go to Step 10.

No

Go to the next step.

6

 INSPECT PCM CONNECTOR CONDITION

  • Disconnect the PCM connector.

  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).

  • Is there any malfunction?

Yes

Repair or replace the connector and/or terminals, then go to Step 10.

No

Go to the next step.

7

 INSPECT THROTTLE VALVE ACTUATOR CIRCUIT FOR SHORT TO POWER SUPPLY

  • Verify that the throttle body and PCM connectors are disconnected.

  • Switch the ignition ON (engine off).

    NOTE:

    • Another DTC may be stored by the PCM detecting an open circuit.

  • Measure the voltage at the following terminals (wiring harness-side):

    • Throttle body terminal E

    • Throttle body terminal F

  • Is the voltage 0 V?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:

  • Throttle body terminal E—PCM terminal 1CG

  • Throttle body terminal F—PCM terminal 1CC

    If there is a common connector:

  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to power supply.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness which has a short to power supply.

Go to Step 10.

8

 INSPECT THROTTLE VALVE ACTUATOR CIRCUIT FOR OPEN CIRCUIT

  • Verify that the throttle body and PCM connectors are disconnected.

  • Switch the ignition off.

  • Inspect for continuity between the following terminals (wiring harness-side):

    • Throttle body terminal E—PCM terminal 1CG

    • Throttle body terminal F—PCM terminal 1CC

  • Is there continuity?

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:

  • Throttle body terminal E—PCM terminal 1CG

  • Throttle body terminal F—PCM terminal 1CC

    If there is a common connector:

  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness which has an open circuit.

Go to Step 10.

9

 INSPECT THROTTLE VALVE

Yes

Replace the throttle body, then go to the next step.

(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Go to the next step.

10

 VERIFY DTC TROUBLESHOOTING COMPLETED

Yes

Repeat the inspection from Step 1.

Go to the next step.

No

Go to the next step.

11

 VERIFY AFTER REPAIR PROCEDURE

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

No

DTC troubleshooting completed.
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Free to use workshop manual for your 2015+ Mk4 'ND' Mazda MX-5

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